The present invention relates to a device which ionizes a sample for the purpose of, for example, mass spectrometry, and a mass spectrometer apparatus with this ionization device.
A liquid chromatograph/mass spectrometer apparatus includes an ionization device serving as an interface between a liquid chromatograph and a mass analyzing unit. Liquid containing sample components and solvent is delivered from the liquid chromatograph into the ionization device where it is ionized for mass spectrometry. More specifically, the liquid from the liquid chromatograph is first introduced into a nebulizer of the ionization device and nebulized. The nebulized liquid is then delivered to a desolvation unit where the solvent molecules are separated from the sample molecules. The sample molecules are further transferred to a location as an ion source in which the sample molecules are ionized. Ions thus produced are delivered to the mass analyzing unit where they undergo mass separation and thereafter they are discharged out of the apparatus.
An example of commonly used or publicly known nebulizers is disclosed in Analytical Chemistry, 1988, vol. 60, pp. 774-780. This nebulizer includes a pipe having an inner diameter of 100 .mu.m or so, and liquid from a liquid chromatograph is injected from the pipe and nebulized. The nebulized liquid is then introduced into a desolvation unit including a pipe whose inner diameter is about 5 mm.
In the conventional nebulizer described above, a space between the two pipes is open to the atmospheric pressure. The liquid is injected to this open space, causing friction between a flow of nebulized mist and the atmosphere. Due to this friction, the surrounding fluid is drawn into the nebulized mist flow, and actively collides with droplets of the nebulized mist, thus making the mist finer.
However, the nebulization space is directly open to the atmosphere, and consequently, drawing of the fluid into the mist in the nebulization space is directly influenced by turbulence of the environment caused by ventilation of the apparatus, temperature difference and the like. Accordingly, stability in ionization of a sample is unfavorably affected, resulting in a problem of deterioration in accuracy of mass spectrometry.